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Fruit Flies Coming From the Drain? The Enzyme Gel That Reaches Them

Tiny flies rising from the sink breed in the slime inside the pipe. Scrub it, then use an enzyme gel that clings and clears what hot water slides past.

By Jamilur Rahman Updated November 5, 2026 · 6 min read

Time
15 min, then nightly for a week
Cost
Under $20
Difficulty
Easy
A kitchen sink drain with the strainer removed and a few tiny flies resting on the rim
In this guide
  1. Quick answer
  2. Free vs. permanent fix
  3. What you'll need
  4. Why it happens
  5. Try this first (free)
  6. When free fixes aren't enough
  7. Buy the fix
  8. Where else they breed: check these before you blame the drain
  9. What to skip
  10. FAQ
  11. Related problems

Quick answer

To get rid of fruit flies in a drain, you have to remove the slime in the pipe where the larvae live, because sprays and traps only kill the adults you can see. Confirm the drain is the source with an overnight tape test, scrub the opening and flush it with hot tap water, then treat it at night with an enzyme drain gel. The gel clings to the pipe wall and digests the film that hot water slides past.

Free fix vs. permanent fix

Free fix · 15 minutes

Tape test, scrub and hot flush

  • Tape clear plastic wrap over the drain overnight to confirm the source
  • Scrub the drain opening and strainer with a stiff brush
  • Flush with hot tap water, not boiling
  • Take out the trash and ripe fruit the same day

How long it lasts: A week or two. Hot water melts grease at the surface, but the film farther down stays, and new flies hatch from it.

Most readers choose Permanent fix
Enzyme drain gel for drain flies (illustration)
Illustration

An enzyme drain gel

Drain flies lay eggs in the wet, greasy film inside the pipe. Hot water and traps only reach the surface. A thick enzyme gel clings to the pipe wall, and the enzymes break down the organic film the larvae feed on, so there is nothing left for them to hatch from.

What to get: Enzyme drain gel for drain flies

How long it lasts: Keeps the film from building back when you use it as the label says, often nightly for a week and then now and then.

Check price on Amazon

As an Amazon Associate I earn from qualifying purchases.

What you'll need

  • Clear tape and plastic wrap

    For the overnight tape test

    You have it

  • Stiff bottle brush or old toothbrush

    To scrub the strainer and the drain throat

    You have it

  • Rubber gloves

    Drain film is not something to touch bare-handed

    You have it
  • Our pick
    Enzyme drain gel (illustration)
    Illustration

    Enzyme drain gel

    Use at night when the sink will sit unused

    Check price
  • Flexible drain cleaning brush (illustration)
    Illustration

    Flexible drain cleaning brush

    Reaches film below the opening

    Check price

Why it happens

1

Slime film inside the pipe

Food bits, grease and soap coat the pipe walls and form a damp, rotting film. Drain flies lay eggs in it, and the larvae feed on it.

2

A dried-out trap in a rarely used drain

Water in the trap evaporates in a sink or floor drain that is not used. Without it, flies and odors can come up from the pipe.

3

A different source nearby

Ripe fruit, a full trash can, a damp mop or a garbage disposal can host true fruit flies that happen to land at the drain. The tape test shows which it is.

Try this first (free)

Do these in order, starting with the simplest.

  1. Run the tape test overnight

    Tool used: Clear tape and plastic wrap

    Tape clear plastic wrap over the drain opening and leave it overnight. In the morning, flies stuck under the wrap mean the drain is the source.

  2. Scrub the opening

    Tool used: Stiff bottle brush or old toothbrush

    Remove the strainer and scrub it and the drain throat with dish soap and a stiff brush. Wear gloves, and do not put a brush into a running disposal.

  3. Flush with hot tap water

    Run the hot tap for a minute or two. Do not pour boiling water down the drain, since it can soften PVC joints and crack porcelain.

  4. Treat the drain with enzyme gel at night

    Tool used: Enzyme drain gel

    Pour in the label amount just before bed and leave it overnight with no water running. Repeat each night for about a week, or as the label says.

    Enzyme drain gel (illustration)
    Illustration

    Tool for this step

    Enzyme drain gel · Use at night when the sink will sit unused

    Check price on Amazon

  5. Remove the other food sources

    Empty the trash, store ripe fruit in the fridge, rinse recycling, and wipe up sticky spills under the dish rack and around the sink. Flies need food as well as a drain.

When free fixes aren't enough

Hot water and scrubbing remove the film you can reach. The film deeper in the pipe is out of reach, and that is where the next generation hatches. If the flies are back within two weeks of a hot flush, the breeding film is farther down than your brush goes, and a gel clings there overnight. If you still see flies after two weeks of nightly treatment, look for another source: the garbage disposal, a leak under the sink, a floor drain, or a dry trap in an unused sink. A sewage smell, or larger flies that spread beyond the kitchen, means a plumber should check for a cracked pipe or a failed trap seal.

Buy the fix

Still stuck after the free fixes? These are the products we would look at.

Our picks compared
PickProductFixesWho it's forBuy
Best pick
Enzyme drain gel for drain flies (illustration)
Illustration
Enzyme drain gel for drain flies
the slime inside the pipe where drain flies breed Anyone still seeing flies after a hot flush, especially with a disposal or a greasy kitchen. Check price
Budget pick
Flexible drain cleaning brush (illustration)
Illustration
Flexible drain cleaning brush
film on the pipe wall just below the opening Anyone who wants to scrub before treating, or to avoid gels. Check price
Best pick
Enzyme drain gel for drain flies (illustration)
Illustration

Enzyme drain gel for drain flies

Fixes: the slime inside the pipe where drain flies breed

Look for: Enzyme or bacteria based, not strong acid or lye, so check the ingredients; A thick gel that clings instead of running straight through; Safe for your pipes and for septic systems if that applies; Label directions for a treatment lasting several nights.

Who it's for
Anyone still seeing flies after a hot flush, especially with a disposal or a greasy kitchen.
Honest downside
The drain is fully blocked, so clear the clog first, or a harsh chemical cleaner has just been used in it. Never mix products.
Check price on Amazon
Budget pick
Flexible drain cleaning brush (illustration)
Illustration

Flexible drain cleaning brush

Fixes: film on the pipe wall just below the opening

Look for: Long enough to reach below the drain opening; Bristles all around the shaft; A diameter that fits your strainer opening, so measure first.

Who it's for
Anyone who wants to scrub before treating, or to avoid gels.
Honest downside
Your drain has a garbage disposal below it. Do not push a brush into a disposal.
Check price on Amazon

As an Amazon Associate I earn from qualifying purchases. We don't show prices because they change, so use the button to see today's price.

How we picked: How we picked: this page is based on pest control extension guides for drain and fruit flies, drain-care advice from plumbing guides, and what owners report about enzyme gels. We do not test products by hand.

Where else they breed: check these before you blame the drain

  • Garbage disposal: food builds up under the splash guard.
  • Trash and recycling: sticky cans and bottles.
  • Damp mops and sponges: wring them out and let them dry.
  • Fruit, onions and potatoes: ripe produce left out on the counter.
  • Floor drains and unused sinks: pour in a cup of water to refill a dry trap.

What to skip

Bleach, boiling water and vinegar traps alone

Bleach and boiling water kill what they touch but do not scrub away the film that houses the larvae. Boiling water can soften PVC joints and crack porcelain. Never mix bleach with vinegar, ammonia or another drain cleaner, since it can release toxic gas. A bowl of vinegar catches a few adults but does nothing about the drain.

Frequently asked questions

Are they fruit flies or drain flies?
Fruit flies are tan with red eyes and hover over ripe fruit. Drain flies, also called moth flies, are small, fuzzy and gray, and they rest on walls near drains. Either can breed in a drain film. The tape test shows whether the drain is the source.
How long does it take to get rid of drain flies?
From egg to adult takes roughly one to three weeks, so give any fix at least two weeks. If you keep treating the drain and removing other food, the numbers drop every few days.
Does baking soda and vinegar kill fruit flies in the drain?
It fizzes and rinses the surface, but it does not clear the film where the larvae live. Use it as a quick freshen-up, not as the cure.
Why do the flies keep coming back after I clean the drain?
Eggs and larvae stay in the film below the part you can reach, or another source such as a fruit bowl, trash or disposal keeps feeding them. Treat the drain nightly for a week and clear the other sources.

As an Amazon Associate I earn from qualifying purchases. Affiliate disclosure

Enzyme drain gel for drain flies (illustration)
Illustration

Our pick: Enzyme drain gel for drain flies

Check price